Ordnance



Patented June 25, 1946 UNITED STATES PAT EN T ORDINANCE Flix Frdrlc Ruau, Deptford, London, England,

assignor to Molins Machine Company Limited,

London, England Application May 10,1944, Serial Nessa-905 7 In Great Britain May 10, 1943 I ;,j.

2 Claims. (Cl. 89-'-24) This invention concerns improvements in or relating to breech-mechanism for ordnance and in particular to breech-mechanism of the type in which the breech-block slides transversely to the axis of the bore and is held open against the ac- 5 tion of springs by retaining catches or extractors which are actuated by the rim'of around when the latter has completely entered the breech-chamber to release the breech-block.

Such breech-block have a substantially concave 10: surface for guiding a round in ramming and a chamfer or bevel extending from said surface to the inner surface of the breech-block (that'is to say the surface which co-operates with the chamber face), so that if the round is not seated as l5,

the block is closed the chamfer or bevel will engage the base of the round and push it home. Such breech-mechanism, which is known as semiautomatic breech-mechanism, is referred to hereinafter as breech-mechanism of the type de- .201

scribed, and the term when used herein is to be considered as including cases in which the rounds are automatically fed and automatically fired.

It has been found that, when guns having:

breech-mechanisms of the type described have been fitted with automatic feeding and ramming mechanism, occasionally the breech, on closing, has become jammed by reason of the round being not completely home. It has also been found that.

this fault has been caused by rebounding of the round as it strikes the chamber face beyond the edge of the breech-block where the bevel termi nates, due it is believed, to the speed at which the round is rammed into the breech-chamber.

Some breech-blocks of the type described slide horizontally and some slide vertically and it will be appreciated that the one is the equivalent of the other so far as the present invention is concemed.

Jams of the nature described are prevented,

according to the present invention, by the provision in breech-mechanism of the type described, of a stop at or in the region of the inner concave edge of the breech-block, said stop being adapted I to move behind a round after the latter has been fully rammed into the'bre'ech-chamber so as to limit rebounding of the round from the breechchamber the position of the stop being such that the base of a round striking the stop on rebounding will be engaged and pushed into the breechchamber by the chamfer of the breech-block as the latter closes, wherein the stop is of substantial width and its top surface is of generally 'cumferential edgeysuch as an outstanding edge where the case overlaps the -projectileand the dge: formed by the projectilefa'nd' its fiat nose. Rounds of this kind'will be referred to; herein and in'the appended claims as rounds as s'pecifiedQ" Althou'ghthe' edge of the rim at thebase of such a round constitutes a circumferential W edge, theexpression circumferential edgeflwhen used inconnection with a round as specified, does not include this edge of the .rim, but only such edgesasare to be inserted in the {breech so as V to pass the chamber-edgeasidefined hereinafter. When rammin rounds of the kind specified, it

sometimes happens that the edge of the flat nose of the round, or the outstanding edge of the case where it overlaps the projectile, catches against I an edge of the breech-chamber,'thusipreventing the round from being properly rammed home and 35 causing a jam. In 'order to prevent jams of this nature, the stop may be so arranged (e.j g. by providing a sprin'g of suitable strength) that as a round is being rammed, 'thesto'p is held 'in its outer position to act to guide any circumferential edge of a roundas specified clear of the chamberedge'but is depressed when the base of a round passes over it. e I

The stop may; be-wedge-shaped in the sense that it provides a lead for. around being rammed.

A breech-block made in accordance with the present invention will now be describedrby way drawing in which:

"Fig-.1 is a sectional elevation of part-10f -a breech-block showing the round-retaining-device and its relation to thelbreech-chamber'when the breech-block is 'held' in'the open position; after I having moved lip from its lowermostposition; Fig. 2 is a frontelevation of;the'breech-block shown in Fig.1; and.

5 '3: is a dia'grammatic view 7 of an example i I f'of'a round as specified. 1-. v

Like reference numerals refer to likefparts' throughout the several figures of the drawing.

The breech-block 5 is arranged to slide vertir .cally upwards to close the breech 3, part of which] only is shown. The usual chamfer-surface'provided at the upper part 53 of the inner surface of; the breech-block which co-operates with" the 55 chamber face C--F, can be clearly seen from the I FicE -"il;

of example with reference to the accompanying drawing. The usual breech-retaining-members which are moved in to release the breech-block when engaged by the rim of a round, are not shown, as being unnecessary for the understanding of the invention.

Reboundi-ng of the round as it strikes the chamber-face is prevented by a stop or retainer-shoe 353. The retainer shoe 353 has a curved upper surface whose curvature substantially con'esponds to that of the concave surface of the breechblOck. This retainer-shoe 353 is, as can be seen from Figure 2, of considerable width/so. that it can during the initial part of the ramming stroke act as a guide and help to centre the nose of the round and thus perform part of the function of the curved top of the breech-block: in addition to performing its subsequent function or trapping the round.

The retainer-shoe 353 also acts as a guide to centre the nose of a round. by reason .of thefact that it remains in its upward or outrrpos'ition while the nose of a round is passing .over it and is not depressed until substantially the whole of the round has entered the breech-chamber.

For this purpose the retainer-shoe is provided w-lth a strongcompression -spring 1-0.8, whichis already artly-compressed whenthe. shoe is. fully up, and is strong enough to resist further compression except by a stronger force than that providedhy-the weight alone ofaround. The purpose of this arrangement is .to'enable rounds as specified to be rammed without jamming. An example of a round as specifiedis shown diagrammaticallyin Figure 3; The round shown has,;

as =canbe seen, a circumferential edge-l5 where thecase overlaps the projectile and also-another circumferential edge I40 formed by the projectile udits flat nose M. Whenrounds of this-kind are rammed into the breech-chambenit some-- basa'the-zrecess L6 will not be present so that the f:

chamber-edge will in such cases. be the edge formed by the chamber and the chamber-face. For convenience the expression chamberaedge is used herein and in the. appended. claims; and

has the meaning given above.

By the provision of the curved retainer-shoe 353, which by reason of. its strong spring is kept in its outer position while the rOlll'ld is being introduced into the breech-chamber, the circumferentia'l edges M1] and [5 can be kept out of con-: tact with the chamber-edge.

As the round moves completely into the breechchamber the. rim of the roundsas it passes over the retainer-shoe forces the latter down, and the shoe springs up again after the rim has, passed it to trap the round should it tend to rebound.

The arrangement of the retainer-shoe 353 on the breech-block is such that the shoe is provided with a spring-barrel I06 slidable in a hole In! in the breech-block 5 and containing the compression-spring I08, slight play existing between said barrel and shoe to provide for their relative movements. The spring-barrel may bedepressed by inserting a small rod or tool through the hole I l E in the shoe, when the shoe can he slipped out. The heel of the shoe fits into the recess 9 in the breech-block.

The shoe 353 is provided with two lugs ll, one at each side, which are arranged to fit into recesses 12 in the breech-block. The purpose of tlns'arrangement is to limit the upward movement of the shoe by engagement of the lugs II with the-upper walls l3 of the recesses.

The retainer shoe as shown in Figure 1, is wedge-shaped in the sense that it slopes upwardly towards the breech-chamber whereby a round can slide forwardly over it, withoutthe rim being caught, but rebounding is preventedby engagement of the round against the steep faceofuthe retainer shoe. l

The breech-block is so arranged relatively to the breech-chamber when the former is "held in the open position that the top of the retainershoe when fully unis in a-position behind the recess in the breech-chamber which accommodates the rim of the cartridge.

What I claim as my invention and desire secure by Letters (Patent is:

3,. In breech-mechanism of the type described, in combination with a breech-chamber and a breech-block slidable transversely of' the axis of the bore of said chamber and in contact with the face thereof, said block having a concave surface for guiding. a round into the breechchamber and a chamfered edge onsaid surface contiguous to. the chamber face, a. stop movably mounted on said block adjacent the chamfered edge thereof, means yieldingly urging said step above the concave surface of the'breech-block into a position behind a round after the latter has been fully rammed into the breech-chamher so as to limit rebounding of the round from the breech-chamber, said stop being .50 constructed and arranged relative tothe charnfered edge of the breech-block that the base of a round striking the stop on reboundingwill he engaged pushed into the breech-chamber by said chamfered edge as the breech-block closes,said stop being relatively wide and having a concave upper surface constituting a guide to help to centre the nose of a round entering the breech-chamber.

2. Breech-mechanism as claimed in claim 1, inv which said yieldingly urging means maintains the stop in a position such that, when a round is being rammed, at least a portion of the upper surface of said stop is above the edge of the breech-chamber so as to guide any circumferential edge of a round clear of the chamber edge, said yieldingly urging means yielding to permit depression of the stop when the base of a round passes over it.

FELIX FRE'DERIC RUAU. 

